1. Field of the Invention
This invention relates to an apparatus for forming a downwardly extending hole in the surface of the earth for seismic exploration or for forming a larger diameter hole such as made during exploratory drilling. The hole forming device includes an elongated rigid planting member having a point or tip at its lower end which is forced downwardly into the earth's surface by a combination of forces. The multiple forces may include a primary downward force exerting a substantially constant downward push on the planting member and either or both additional forces imparted to the planting member when the primary force no longer moves the planting member downwardly. The additional forces include a vibrating force applied to the planting member and a force formed by injection of high pressure low volume liquid into a subsurface formation from the lower end of the planting member to separate, saturate, liquefy or condition a compacted or resistant formation to enable penetration of a formation structure that resists penetration by the downward force.
2. Description of the Prior Art
U.S. Pat. No. 5,281,775 issued Jan. 25, 1994 discloses a hole forming device in the form of a vertically moveable pipe planting member having a point on the lower end which is moved downwardly and when a resistance to downward movement is encountered which stops or substantially slows movement of the planting pipe, a vibration force is then applied to the planting pipe to move the planting pipe downwardly through the resisting formation structure.
U.S. Pat. No. 5,343,002 issued Aug. 30, 1994 discloses a disposable point mounted on the lower end of a planting pipe which remains in the formed hole when the planting pipe is retracted and removed.
The prior art of record in the above two patents disclose devices relating to this field of endeavor. The prior patents of record are as follows:
______________________________________ 3,106,258 4,278,025 3,242,999 4,471,669 3,394,766 4,546,703 3,752,242 4,553,443 3,920,083 4,819,740 3,939,771 ______________________________________
The above patents do not disclose a hole forming device for seismic exploration utilizing multiple forces as disclosed in this invention.